Light amplification device and related system and method

Abstract

The embodiment of the invention discloses a light amplification device and a related system and method. The light amplification device comprises an optical fiber isolator, a pump light source, a beam combiner and an EYDF. A large amount of pump light in the EYDF cannot be completely absorbed by ytterbium ions, and ytterbium-band ASE light generated by the ytterbium ions can be further amplified by the pump light, so that effective amplification of signal light by the pump light is limited by the ytterbium-band ASE light. According to the embodiment of the invention, the optical fiber isolator in the light amplification device is modified, the optical fiber isolator can reflect the ytterbium-band ASE light as an auxiliary signal back to the EYDF, the excited amplification of the auxiliary signal and the absorption of the auxiliary signal by the EYDF can effectively inhibit the EYDF from generating the ytterbium-band ASE light, the self-oscillation and self-pulsation of the ytterbium-band ASE light are avoided, and the reliability of the light amplification device is improved. Therefore, the pumping conversion efficiency and the stability of the output power are improved. Meanwhile, the optical amplification device provided by the embodiment of the invention can effectively inhibit the EYDF from generating the ytterbium-band ASE light without adding an additional device, and is beneficial to reducing the cost and the power consumption.

Description

Technical Field

[0001] The present application relates to the field of optical transmission, and in particular to an optical amplification device and related systems and methods. Background Art

[0002] With the rapid development of application scenarios such as optical communications, high-power industrial lasers, and lidar, high-power amplification of 1.5um band lasers has received great attention from the industry. Erbium-doped fiber amplifiers (EDFA) are the main gain medium for amplifying the power of 1.5um input light, but due to the low absorption cross section and low doping concentration of erbium ions, it is difficult for EDFA to achieve high-power amplification of input light. To solve the above problems, currently, a certain concentration of ytterbium ions is doped in the core of the erbium-doped fiber, and a double-clad fiber structure is used, so that a low-cost high-power multi-mode pump can be used as the excitation source of the gain fiber, and the ytterbium ions have a large absorption cross section and a population inversion rate for the pump light, so as to achieve high-efficiency amplification of erbium ions. In addition, thanks to the ytterbium ion doping, the ytterbium ions surrounding the erbium ions can effectively avoid erbium ion clusters, thereby further increasing the erbium ion doping concentration and obtaining high-power and high-efficiency amplification of the input signal light.

[0003] However, when the pump power is further increased to obtain higher amplification power, a large amount of pump light in the Erbium-Ytterbium co-doped fiber (EYDF) cannot be completely absorbed by the ytterbium ions, and the amplified spontaneous emission (ASE) generated by the ytterbium ions will be further amplified by the gain fiber, resulting in the ASE in the 1um band limiting the effective amplification of the pump light on the 1.5um band signal light. Since high-power 1um band ASE is prone to self-pulsation and self-excited oscillation, it is very easy to damage the optical components in the optical amplifier link. Therefore, in order to achieve high-power signal light amplification in the 1.5um band, it is urgent to adopt appropriate technology to suppress the ASE generated by ytterbium ions in the 1um band. Summary of the invention

[0004] The embodiments of the present application provide an optical amplification device and related systems and methods, which can effectively suppress the generation of ytterbium-band ASE light by EYDF, avoid the self-oscillation and self-pulsation of ytterbium-band ASE light, thereby improving the pump conversion efficiency and the stability of the output power.

[0005] In the first aspect, an embodiment of the present application provides an optical amplifier device. The optical amplifier device includes: a first optical fiber isolator, a first pump light source, a first beam combiner and a first erbium-ytterbium co-doped fiber (EYDF). The first optical fiber isolator is used to transmit the signal light from the signal light source to the first EYDF. The first pump light source is used to output the first pump light. The first beam combiner is used to couple the first pump light to the first EYDF. Among them, a large amount of the first pump light in the first EYDF cannot be completely absorbed by the ytterbium ions, and the first ytterbium band amplified spontaneous emission (ASE) light generated by the ytterbium ions will be further amplified by the first pump light, resulting in the first ytterbium band ASE light limiting the effective amplification of the signal light by the first pump light. Among them, the first ytterbium band ASE light can also be called 1um band ASE light, and the first ytterbium band ASE light will be transmitted in the same and opposite directions as the signal light transmission direction. The embodiment of the present application transforms the first optical fiber isolator, and the first optical fiber isolator can reflect the first ytterbium band ASE light as an auxiliary signal back to the first EYDF.

[0006] In this embodiment, the first optical fiber isolator can reflect the first ytterbium band ASE light as an auxiliary signal back to the first EYDF. The stimulated amplification of the auxiliary signal and its absorption by the first EYDF again can effectively suppress the first EYDF from generating ytterbium band ASE light, avoiding the self-oscillation and self-pulsation of the ytterbium band ASE light, thereby improving the pump conversion efficiency and the stability of the output power. At the same time, the optical amplifier device provided in the embodiment of the present application can effectively suppress the first EYDF from generating ytterbium band ASE light without adding additional devices, which is conducive to reducing costs and power consumption.

[0007] In some possible implementations, the first optical fiber isolator includes a first collimator, an isolator, a second collimator, and a reflective element. The first collimator and the second collimator are respectively located at two ends of the first optical fiber isolator, the first collimator is close to the signal light source, the second collimator is close to the first EYDF, and the reflective element is located between the isolator and the second collimator. The reflective element is used to reflect the first ytterbium band ASE light back to the first EYDF. This implementation provides a specific implementation method of an optical fiber isolator, in which a reflective element is added to the original structure of the optical fiber isolator, which is simple to implement and has low cost.

[0008] In some possible implementations, the reflective element is a reflective film located on the end surface of the second collimator, or the reflective element is a reflective film located on the end surface of the isolator. It should be understood that the insertion loss introduced by the reflective film coating method is lower and the practical effect is better.

[0009] In some possible implementations, the reflective element is a dielectric mirror located between the isolator and the second collimator, which expands the implementation method of the embodiment of the present application.

[0010] In some possible implementations, the reflective element is used to reflect light with a wavelength smaller than the wavelength of the signal light and transmit light with a wavelength greater than or equal to the wavelength of the signal light, thereby being adaptable to most signal light transmission scenarios.

[0011] In some possible implementations, the first beam combiner is located between the first fiber isolator and the first EYDF, and the first pump light and the signal light have the same transmission direction. In other words, the embodiment of the present application can be adapted to the application scenario of forward pumping and has a good practical effect.

[0012] In some possible implementations, the first EYDF is coated on a side away from the first beam combiner to reflect the first pump light that is not completely absorbed by the first EYDF back to the first EYDF. In other words, the first pump light that is not completely absorbed by the first EYDF will be reflected back by the dielectric film so that the first pump light is reabsorbed, thereby improving the pumping efficiency.

[0013] In some possible implementations, the first combiner is connected to a side of the first EYDF away from the first fiber isolator, and the transmission directions of the first pump light and the signal light are opposite. That is, the embodiment of the present application can also be adapted to the application scenario of backward pumping, and has good adaptability.

[0014] In some possible implementations, the first optical fiber isolator is further used to suppress the first pump light from being transmitted to the signal light source, thereby effectively protecting the signal light source.

[0015] In some possible implementations, the optical amplification device further includes a second optical fiber isolator, a second pump light source, a second combiner, and a second EYDF, and the signal light from the first EYDF is transmitted to the second EYDF through the second optical fiber isolator. The second pump light source is used to output the second pump light. The second combiner is used to couple the second pump light to the second EYDF, wherein the second ASE light generated in the second EYDF is transmitted in the same direction and in the opposite direction to the signal light transmission direction. The second optical fiber isolator is used to reflect the second ytterbium band ASE light back to the second EYDF. In other words, the embodiment of the present application can also achieve higher power optical amplification through a cascade design.

[0016] In some possible implementations, the first EYDF includes an outer cladding, an inner cladding and a core, the outer cladding wraps the inner cladding, the inner cladding wraps the core, the signal light and the first ytterbium band ASE light are transmitted in the core, and the first pump light is transmitted in the inner cladding.

[0017] In some possible implementations, the wavelength of the signal light is greater than the wavelength of the first ytterbium band ASE light, and the wavelength of the first ytterbium band ASE light is greater than the wavelength of the first pump light.

[0018] In a second aspect, an embodiment of the present application provides an optical amplification system, which includes a signal light source, a first lens group, and an optical amplification device as described in any embodiment of the first aspect. Specifically, the signal light source is used to output signal light. The optical amplification device is used to amplify the signal light. The first lens group is used to collimate the signal light from the EYDF in the optical amplification device.

[0019] In some possible implementations, the optical amplification system further includes a second lens group, and the second lens group is used to process the signal light passing through the first lens group, including but not limited to beam expansion, beam splitting and / or beam combining.

[0020] In a third aspect, an embodiment of the present application provides a radar system, which includes a signal light source, a light receiving device, and a light amplifying device as described in any embodiment of the first aspect. Specifically, the signal light source is used to output signal light. The light amplifying device is used to amplify the signal light and transmit it to a target object. The light receiving device is used to receive the signal light reflected by the target object.

[0021] In a fourth aspect, an embodiment of the present application further provides an optical amplification method, which is applied to an optical amplification device, and the optical amplification device includes: a first optical fiber isolator, a first pump light source, a first combiner and a first EYDF. The optical amplification method includes: transmitting a signal light from a signal light source to a first EYDF through a first optical fiber isolator. Outputting a first pump light through a first pump light source. Coupling the first pump light to the first EYDF through a first combiner, wherein a first ytterbium-band amplified spontaneous emission (ASE) light generated in the first EYDF is transmitted in the same direction and in the opposite direction to the transmission direction of the signal light. Reflecting the first ytterbium-band ASE light back to the first EYDF through the first optical fiber isolator.

[0022] In this embodiment, the first optical fiber isolator can reflect the first ytterbium band ASE light as an auxiliary signal back to the first EYDF. The stimulated amplification of the auxiliary signal and its absorption by the first EYDF again can effectively suppress the first EYDF from generating ytterbium band ASE light, avoiding the self-oscillation and self-pulsation of the ytterbium band ASE light, thereby improving the pump conversion efficiency and the stability of the output power. At the same time, the optical amplifier device provided in the embodiment of the present application can effectively suppress the first EYDF from generating ytterbium band ASE light without adding additional devices, which is conducive to reducing costs and power consumption.

[0023] In some possible implementations, the first optical fiber isolator includes a first collimator, an isolator, a second collimator and a reflective element, the first collimator and the second collimator are respectively located at two ends of the first optical fiber isolator, the first collimator is close to the signal light source, the second collimator is close to the first EYDF, and the reflective element is located between the isolator and the second collimator. Reflecting the first ytterbium band ASE light back to the first EYDF through the first optical fiber isolator includes: reflecting the first ytterbium band ASE light back to the first EYDF through the reflective element. This implementation provides a specific implementation method of an optical fiber isolator, in which a reflective element is added to the original structure of the optical fiber isolator, which is simple to implement and has low cost.

[0024] In some possible implementations, the reflective element is a reflective film located on the end surface of the second collimator, or the reflective element is a reflective film located on the end surface of the isolator. It should be understood that the insertion loss introduced by the reflective film coating method is lower and the practical effect is better.

[0025] In some possible implementations, the reflective element is a dielectric mirror located between the isolator and the second collimator, which expands the implementation method of the embodiment of the present application.

[0026] In some possible implementations, the reflective element is used to reflect light with a wavelength smaller than the wavelength of the signal light and transmit light with a wavelength greater than or equal to the wavelength of the signal light, thereby being adaptable to most signal light transmission scenarios.

[0027] In some possible implementations, the first beam combiner is located between the first fiber isolator and the first EYDF, and the first pump light and the signal light have the same transmission direction. In other words, the embodiment of the present application can be adapted to the application scenario of forward pumping and has a good practical effect.

[0028] The first EYDF at one side away from the first beam combiner reflects the first pump light not completely absorbed by the first EYDF back to the first EYDF through coating. In other words, the first pump light not completely absorbed by the first EYDF will be reflected back by the dielectric film so that the first pump light is reabsorbed, thereby improving the pumping efficiency.

[0029] In some possible implementations, the first combiner is connected to a side of the first EYDF away from the first fiber isolator, and the transmission directions of the first pump light and the signal light are opposite. That is, the embodiment of the present application can also be adapted to the application scenario of backward pumping, and has good adaptability.

[0030] In some possible implementations, the method further includes: suppressing the first pump light from being transmitted to the signal light source by a first optical fiber isolator, thereby effectively protecting the signal light source.

[0031] In some possible implementations, the optical amplification device further includes a second optical fiber isolator, a second pump light source, a second combiner, and a second EYDF, and the signal light from the first EYDF is transmitted to the second EYDF through the second optical fiber isolator. The method further includes: outputting a second pump light through a second pump light source. Coupling the second pump light to the second EYDF through a second combiner, wherein the second ASE light generated in the second EYDF is transmitted in the same direction and in the opposite direction to the signal light transmission direction. : Reflecting the second ytterbium band ASE light back to the second EYDF through the second optical fiber isolator. That is, the embodiment of the present application can also achieve higher power optical amplification through a cascade design.

[0032] In some possible implementations, the first EYDF includes an outer cladding, an inner cladding and a core, the outer cladding wraps the inner cladding, the inner cladding wraps the core, the signal light and the first ytterbium band ASE light are transmitted in the core, and the first pump light is transmitted in the inner cladding.

[0033] In some possible implementations, the wavelength of the signal light is greater than the wavelength of the first ytterbium band ASE light, and the wavelength of the first ytterbium band ASE light is greater than the wavelength of the first pump light.

[0034] In the embodiment of the present application, the combiner couples the signal light and the pump light to the EYDF, and the ytterbium-band ASE light generated in the EYDF is transmitted in the same direction and the opposite direction as the signal light transmission direction. The embodiment of the present application has modified the fiber isolator in the optical amplifier device, and the fiber isolator can reflect the ytterbium-band ASE light back to the EYDF as an auxiliary signal. The stimulated amplification of the auxiliary signal and its absorption by the EYDF again can effectively suppress the generation of ytterbium-band ASE light by the EYDF, avoiding the self-oscillation and self-pulsation of the ytterbium-band ASE light, thereby improving the pump conversion efficiency and the stability of the output power. At the same time, the optical amplifier device provided in the embodiment of the present application can effectively suppress the generation of ytterbium-band ASE light by the EYDF without adding additional devices, which is beneficial to reducing costs and power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the first structure of the optical amplifying device in the embodiment of the present application;

[0036] Figure 2 This is a schematic diagram of the first structure of the optical fiber isolator in the embodiment of the present application;

[0037] Figure 3 This is a schematic diagram of the second structure of the optical fiber isolator in the embodiment of the present application;

[0038] Figure 4 This is a schematic diagram of the third structure of the optical fiber isolator in the embodiment of the present application;

[0039] Figure 5A schematic diagram of the structure of EYDF in an embodiment of the present application;

[0040] Figure 6 This is a schematic diagram of a second structure of the optical amplifying device in an embodiment of the present application;

[0041] Figure 7 This is a schematic diagram of a third structure of the optical amplifying device in an embodiment of the present application;

[0042] Figure 8 A schematic diagram of an embodiment of the light amplification method in the embodiment of the present application;

[0043] Fig. 9 A schematic diagram of an optical amplification system in an embodiment of the present application;

[0044] Fig.10 Schematic diagram of a radar system in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The embodiment of the present application provides an optical amplifier device and related systems and methods, which can effectively suppress the generation of ytterbium-ytterbium co-doped fiber (EYDF) amplified spontaneous emission (ASE) light in the ytterbium band, avoid the self-oscillation and self-pulsation of the ytterbium-band ASE light, and thus improve the pump conversion efficiency and the stability of the output power. It should be understood that the optical amplifier device provided in the embodiment of the present application can also be referred to as an erbium-ytterbium co-doped fiber amplifier (EYDFA). For example, EYDFA can be used in scenarios such as space optical communications and optical fiber communication links; for another example, EYDFA can be used in vehicle-mounted laser radars to achieve high-efficiency amplification of pulsed light; for another example, EYDFA can be used as an optical amplifier for industrial laser processing to significantly increase the output power of the input laser.

[0046] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, rather than to limit a specific order or precedence. It should be understood that the above terms can be interchanged where appropriate, so that the embodiments described in this application can be implemented in a sequence other than the content described in this application. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0047] Figure 1 Schematic diagram of the first structure of the optical amplifier device in the embodiment of the present application. Figure 1 As shown, the signal light source 10 is used to output signal light. The optical amplification device includes: an optical fiber isolator 20, a pump light source 30, a combiner 40 and an EYDF 50. The signal light is transmitted to the combiner 40 through the optical fiber isolator 20. The optical fiber isolator 20 is used to isolate the echo reflected light generated by the signal light transmission, so as to ensure that the signal light has a single transmission direction. The pump light source 30 is used to output the pump light to the combiner 40. The combiner 40 is used to couple the signal light and the pump light to the EYDF 50, and the signal light and the pump light in the EYDF 50 are transmitted in the same direction, and the signal light is amplified by the EYDF 50. It should be understood that in actual applications, the signal light source 10 refers to a signal light emitting device, such as an optical module, etc., and the optical amplification device may include the signal light source 10, or may not include the signal light source 10, and the specific details are not limited here.

[0048] Among them, EYDF 50 adopts a double cladding structure, that is, EYDF 50 includes an outer cladding, an inner cladding and a core, the outer cladding wraps the inner cladding, the inner cladding wraps the core, and the signal light is transmitted in the core. The pump light is injected into the inner cladding, the refractive index of the inner cladding is greater than the refractive index of the outer cladding, the outer cladding constitutes a total reflection condition for the pump light, and the pump light is transmitted by reflection in the inner cladding. As an example, the signal light source 10 connected to the optical fiber isolator 20 and the optical fiber isolator connected to the combiner 40 can use a single-mode optical fiber, and the pump light source 30 connected to the combiner 40 can use a multi-mode optical fiber. Among them, the core of the single-mode optical fiber can be connected to the core of the EYDF 50, and the signal light is transmitted to the core of the EYDF 50 through the core of the single-mode optical fiber.

[0049] It should be understood that a large amount of pump light in the EYDF 50 cannot be completely absorbed by the ytterbium ions, and the ytterbium-band ASE light generated by the ytterbium ions will be further amplified by the pump light, resulting in the ytterbium-band ASE light limiting the effective amplification of the pump light on the signal light. Among them, the ytterbium-band ASE light can also be called the 1um-band ASE light, and the ytterbium-band ASE light will be transmitted in the same and opposite directions as the signal light transmission direction. The embodiment of the present application has modified the optical fiber isolator 20 in the optical amplifier device, and the optical fiber isolator 20 can reflect the ytterbium-band ASE light back to the EYDF 50 as an auxiliary signal. The stimulated amplification of the auxiliary signal and its absorption by the EYDF again can effectively suppress the EYDF from generating the ytterbium-band ASE light, avoiding the self-oscillation and self-pulsation of the ytterbium-band ASE light, thereby improving the pump conversion efficiency and the stability of the output power. Several possible structures of the optical fiber isolator 20 are introduced below.

[0050] Figure 2 FIG. 1 is a schematic diagram of the first structure of the optical fiber isolator in the embodiment of the present application. Figure 2 As shown, the optical fiber isolator 20 includes a first collimator 201, an isolator 202, a second collimator 203 and a dielectric reflector 204. The first collimator 201 and the second collimator 203 are respectively located at two ends of the optical fiber isolator 20, and the isolator 202 is located between the first collimator 201 and the second collimator 203. The first collimator 201 is used to collimate the signal light diverging from the optical fiber to obtain the signal light transmitted in parallel in space, and the second collimator 203 is used to couple the signal light passing through the isolator 202 into the optical fiber. Among them, the dielectric reflector 204 is located between the isolator 202 and the second collimator 203, and the dielectric reflector 204 is used to transmit the signal light and reflect the ytterbium band ASE light back to the EYDF 50.

[0051] Figure 3 FIG. 2 is a schematic diagram of the second structure of the optical fiber isolator in the embodiment of the present application. Figure 2 The structure shown, such as Figure 3 As shown, a reflective film 205 is plated on the end surface of the second collimator 203 close to the isolator 202. The reflective film 205 has the same function as the dielectric reflector 204, which is used to transmit the signal light and reflect the ytterbium band ASE light back to the EYDF 50.

[0052] Figure 4 FIG. 1 is a schematic diagram of the third structure of the optical fiber isolator in the embodiment of the present application. Figure 2 and Figure 3 The structure shown, such as Figure 4 As shown, a reflective film 206 is coated on the end surface of the isolator 202 close to the second collimator 203. The reflective film 206 has the same function as the dielectric reflector 204, which is used to transmit the signal light and reflect the ytterbium band ASE light back to the EYDF 50.

[0053] It should be understood that in the above Figure 3 and Figure 4 In the optical fiber isolator shown, the insertion loss introduced by coating a reflective film is lower than that by adding a dielectric reflector. It should be noted that, under normal circumstances, the wavelength of the signal light is greater than the wavelength of the ytterbium band ASE light, and the wavelength of the ytterbium band ASE light is greater than the wavelength of the pump light. For example, the signal light is in the 1.5um band, the ytterbium band ASE light is in the 1um band, and the wavelength of the pump light is ≤980nm, and typical values ​​include 915nm, 940nm and 976nm. The embodiment of the present application can design the dielectric reflector 204, the reflective film 205 and the reflective film 206 according to the wavelength of the signal light and the wavelength of the ytterbium band ASE light in actual applications, which is not limited here. For example, the dielectric reflector 204, the reflective film 205 and the reflective film 206 reflect light with a wavelength less than 1.2um, and the reflectivity ranges from 10% to 99.9%.

[0054] Figure 5Schematic diagram of the structure of EYDF in the embodiment of the present application. Figure 1 Taking the optical fiber isolator shown as an example, a dielectric film can be coated on the end face of the EYDF 50 away from the combiner 40. The dielectric film is used to transmit the signal light and reflect the pump light. For example, the dielectric film can be a dichroic mirror. In other words, the pump light that is not completely absorbed by the EYDF 50 will be reflected back by the dielectric film so that the pump light is reabsorbed, thereby improving the pump efficiency. For example, the dielectric film can reflect pump light in the wavelength range of 915nm to 980nm. It should be understood that in some possible scenarios, the end of the EYDF 50 away from the combiner 40 is used to connect to the passive optical fiber, and a dielectric film can also be coated on the end face of the connected passive optical fiber to achieve a similar effect. Alternatively, other reflective elements with similar functions can be set on the side of the EYDF 50 away from the combiner 40.

[0055] It should be understood that Figure 1 The implementation method adopted is forward pumping, that is, the signal light source 10 and the pump light source 30 are both located at the front end of the EYDF 50, and the transmission direction of the signal light and the pump light is the same. In addition, the embodiment of the present application can also adopt the implementation method of backward pumping, which is described below.

[0056] Figure 6 FIG. 2 is a schematic diagram of a second structure of the optical amplifier device in the embodiment of the present application. Figure 6 As shown, the combiner 40 is connected to the side of the EYDF 50 away from the fiber isolator 20, and the transmission directions of the pump light and the signal light are opposite. In this scenario, the fiber isolator 20 can also transmit the signal light and the Ytterbium band ASE light. In addition, the fiber isolator 20 can also suppress the pump light from transmitting to the signal light source 10. Figure 6 In the optical amplifier device shown in the figure, the optical fiber isolator 20 can also adopt the above Figures 2 to 4 Any implementation method will not be described here.

[0057] Figure 7 FIG. 1 is a schematic diagram of a third structure of the optical amplifier device in the embodiment of the present application. Figure 7 As shown in the above Figure 1On the basis of the optical amplifier device shown, higher power optical amplification can also be achieved through a cascade design. As an example, the optical amplifier device also includes an optical fiber isolator 60, a pump light source 70, a combiner 80 and an EYDF 90. The rear end of the EYDF 50 is connected to the optical fiber isolator 60, and the optical fiber isolator 60 is connected to the EYDF 90 through the combiner 80. The combiner 80 is used to couple the pump light output by the pump light source 70 to the EYDF 90. Among them, the optical fiber isolator 60 adopts a design similar to that of the optical fiber isolator 20, and the optical fiber isolator 60 can reflect the ytterbium band ASE light from the EYDF 90 back to the EYDF 90. A dielectric film can also be coated on the end face of the EYDF 90 away from the combiner 80. The dielectric film is used to transmit the signal light and reflect the pump light. The pump light that is not completely absorbed by the EYDF 90 will be reflected back by the dielectric film so that the pump light is reabsorbed, thereby improving the pump efficiency. For details, please refer to Figure 5 It should be understood that it is also possible to Figure 6 The optical amplifier device shown in the figure is based on a similar Figure 7 The cascade design shown will not be described in detail here.

[0058] From the above introduction, it can be seen that the embodiment of the present application has modified the optical fiber isolator in the optical amplifier device. The optical fiber isolator can reflect the ytterbium band ASE light as an auxiliary signal back to the EYDF. The stimulated amplification of the auxiliary signal and its absorption by the EYDF again can effectively suppress the EYDF from generating the ytterbium band ASE light, avoiding the self-oscillation and self-pulsation of the ytterbium band ASE light, thereby improving the pump conversion efficiency and the stability of the output power. At the same time, the optical amplifier device provided in the embodiment of the present application can effectively suppress the EYDF from generating the ytterbium band ASE light without adding additional devices, which is conducive to reducing costs and power consumption.

[0059] The optical amplification method provided in the embodiments of the present application is introduced below.

[0060] Figure 8 Schematic diagram of an embodiment of the optical amplification method in the embodiment of the present application. It should be noted that the optical amplification method is implemented based on the optical amplification device introduced above. For the introduction of the optical amplification device, reference can be made to the relevant descriptions of the above embodiments, which will not be repeated here. In this example, the optical amplification method includes the following steps.

[0061] 11. Transmit the signal light from the signal light source to the EYDF through the optical fiber isolator.

[0062] The optical fiber isolator isolates the echo reflected light generated by the signal light transmission, thereby ensuring that the signal light has a single transmission direction. Figure 1 In the forward pumping scenario shown, the signal light passing through the fiber isolator is also transmitted to the core of the EYDF through the combiner. Figure 6 In the backward pumping scenario shown, the signal light is transmitted directly into the core of the EYDF after passing through the fiber isolator.

[0063] 12. Output pump light through a pump light source.

[0064] 13. Couple the pump light to the EYDF through a beam combiner.

[0065] Specifically, the EYDF adopts a double-cladding structure, and the beam combiner can couple the pump light into the inner cladding of the EYDF, and the pump light is transmitted in the inner cladding by reflection.

[0066] 14. The Ytterbium-band ASE light is reflected back to the EYDF through the fiber isolator.

[0067] A large amount of pump light in EYDF cannot be completely absorbed by ytterbium ions. The ytterbium-band ASE light generated by ytterbium ions will be further amplified by the pump light, resulting in the ytterbium-band ASE light limiting the effective amplification of the pump light on the signal light. The ytterbium-band ASE light will be transmitted in the same and opposite directions as the signal light transmission direction. The ytterbium-band ASE light can be reflected back to the EYDF as an auxiliary signal through the fiber isolator. The stimulated amplification of the auxiliary signal and its absorption by the EYDF again can effectively suppress the generation of ytterbium-band ASE light by the EYDF, avoiding the self-oscillation and self-pulsation of the ytterbium-band ASE light, thereby improving the pump conversion efficiency and the stability of the output power.

[0068] The following is an introduction to possible application scenarios of the above optical amplification device.

[0069] Fig. 9 Schematic diagram of an optical amplification system in an embodiment of the present application. Fig. 9 As shown, the optical amplification system includes a signal light source 21, an optical amplification device 22, and a first lens group 23. The optical amplification device 22 can be an optical amplification device as described in any of the above embodiments. Specifically, the optical amplification device 22 amplifies the signal light output by the signal light source 21, and the amplified signal light is transmitted to the first lens group 23 through the EYDF in the optical amplification device 22. The first lens group 23 collimates the signal light diverging from the EYDF to obtain the signal light transmitted in parallel in space. Optionally, the optical amplification system also includes a second lens group 24, and the second lens group 24 can process the signal light transmitted in parallel in space according to actual needs, including but not limited to beam expansion, beam splitting and beam combining.

[0070] Fig.10 Schematic diagram of a radar system in an embodiment of the present application. Fig.10As shown, the radar system includes a signal light source 31, an optical amplifier 32 and an optical receiver 33. Among them, the optical amplifier 32 can be an optical amplifier as described in any of the above embodiments. Specifically, the optical amplifier 32 amplifies the signal light output by the signal light source 31, and transmits the amplified signal light to the target object. The optical receiver 33 receives the light beam reflected by the target object. The light beam receiving device can process the received light beam to calculate the flight time of the light beam, thereby realizing the radar ranging function. It should be understood that the signal light source 31 can specifically be a pulse signal source. In a possible scenario, the signal light source 31 and the optical amplifier 32 can also be integrated together.

[0071] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical amplification device, characterized in that: include: A first optical fiber isolator, a first pump light source, a first beam combiner and a first erbium-ytterbium co-doped optical fiber EYDF; The first optical fiber isolator is used to transmit the signal light from the signal light source to the first EYDF; The first pump light source is used to output a first pump light; The first beam combiner is used to couple the first pump light to the first EYDF, wherein the first ytterbium-band amplified spontaneous emission (ASE) light generated in the first EYDF is transmitted in the same direction as and in the opposite direction to the transmission direction of the signal light; The first optical fiber isolator is used to reflect the first ytterbium-band ASE light back to the first EYDF.

2. The optical amplifier device according to claim 1, characterized in that: The first optical fiber isolator includes a first collimator, an isolator, a second collimator and a reflective element. The first collimator and the second collimator are respectively located at two ends of the first optical fiber isolator. The first collimator is close to the signal light source, and the second collimator is close to the first EYDF. The reflective element is located between the isolator and the second collimator, and the reflective element is used to reflect the first ytterbium band ASE light back to the first EYDF.

3. The optical amplification device according to claim 2, characterized in that: The reflective element is a reflective film located on an end surface of the second collimator, or the reflective element is a reflective film located on an end surface of the isolator.

4. The optical amplification device according to claim 2, characterized in that: The reflective element is a dielectric mirror located between the isolator and the second collimator.

5. The optical amplification device according to any one of claims 2 to 4, characterized in that: The reflective element is used to reflect light whose wavelength is smaller than the wavelength of the signal light.

6. The optical amplification device according to any one of claims 1 to 5, characterized in that: The first beam combiner is located between the first optical fiber isolator and the first EYDF, and the first pump light and the signal light have the same transmission direction.

7. The optical amplifier device according to claim 6, characterized in that: The first EYDF reflects the first pump light that is not completely absorbed by the first EYDF back to the first EYDF through coating on one side of the first EYDF away from the first beam combiner.

8. The optical amplification device according to any one of claims 1 to 5, characterized in that: The first beam combiner is connected to a side of the first EYDF away from the first optical fiber isolator, and the transmission directions of the first pump light and the signal light are opposite.

9. The optical amplifying device according to claim 8, characterized in that: The first optical fiber isolator is further used to suppress the first pump light from being transmitted to the signal light source.

10. The optical amplification device according to any one of claims 1 to 9, characterized in that: The optical amplification device further includes a second optical fiber isolator, a second pump light source, a second beam combiner and a second EYDF, and the signal light from the first EYDF is transmitted to the second EYDF through the second optical fiber isolator; The second pump light source is used to output a second pump light; The second combiner is used to couple the second pump light to the second EYDF, wherein the second ASE light generated in the second EYDF is transmitted in the same direction as and in the opposite direction to the transmission direction of the signal light; The second optical fiber isolator is used to reflect the second ytterbium band ASE light back to the second EYDF.

11. The optical amplification device according to any one of claims 1 to 10, characterized in that: The first EYDF includes an outer cladding, an inner cladding and a core, the outer cladding wraps the inner cladding, the inner cladding wraps the core, the signal light and the first ytterbium band ASE light are transmitted in the core, and the first pump light is transmitted in the inner cladding.

12. The optical amplification device according to any one of claims 1 to 11, characterized in that: The wavelength of the signal light is greater than the wavelength of the first ytterbium-band ASE light, and the wavelength of the first ytterbium-band ASE light is greater than the wavelength of the first pump light.

13. An optical amplification system, characterized in that: The optical amplifier comprises a light amplifying device, a signal light source and a first lens group as claimed in any one of claims 1 to 12; The signal light source is used to output signal light; The optical amplifying device is used to amplify the signal light; The first lens group is used to collimate the signal light from the erbium-ytterbium co-doped optical fiber EYDF in the optical amplification device.

14. The optical amplification system according to claim 13, characterized in that: The optical amplification system further includes a second lens group; The second lens group is used to expand, split and / or combine the signal light passing through the first lens group.

15. A radar system, characterized in that: The optical amplifier, signal light source and optical receiving device according to any one of claims 1 to 12; The signal light source is used to output signal light; The optical amplifying device is used to amplify the signal light and transmit it to a target object; The light receiving device is used to receive the signal light reflected by the target object.

16. A light amplification method, characterized in that: The optical amplification method is applied to an optical amplification device, which includes: a first optical fiber isolator, a first pump light source, a first beam combiner and a first erbium-ytterbium co-doped optical fiber EYDF; the optical amplification method includes: transmitting the signal light from the signal light source to the first EYDF through the first optical fiber isolator; outputting a first pump light through the first pump light source; coupling the first pump light to the first EYDF through the first beam combiner, wherein the first ytterbium-band amplified spontaneous emission (ASE) light generated in the first EYDF is transmitted in the same direction as and in the opposite direction to the transmission direction of the signal light; The first ytterbium-band ASE light is reflected back to the first EYDF through the first optical fiber isolator.

17. The method according to claim 16, characterized in that The first optical fiber isolator comprises a first collimator, an isolator, a second collimator and a reflective element, the first collimator and the second collimator are respectively located at two ends of the first optical fiber isolator, the first collimator is close to the signal light source, the second collimator is close to the first EYDF, and the reflective element is located between the isolator and the second collimator; Reflecting the first ytterbium band ASE light back to the first EYDF through the first optical fiber isolator comprises: The first ytterbium-band ASE light is reflected back to the first EYDF by the reflective element.

18. The method according to claim 17, characterized in that The first reflective element is a reflective film located on an end surface of the second collimator, or the first reflective element is a reflective film located on an end surface of the isolator.

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